Idle adjusting tool

ABSTRACT

An idle adjusting tool has a body adapted for mounting on a fuel-air mixer with a bore of the body opening into a fuel passage of the mixer. A spring biases a screwdriver blade, received in the bore, away from an idle adjusting screw of the mixer. Upon displacing the screwdriver blade against the force of the spring, it is possible to engage the idle adjusting screw. Gas pressure communication between the fuel passage and a pressure gauge connected to the tool exists through the bore.

United States Patent McJones [451 Mar. 21, 1972 54 IDLE ADJUSTING TOOL [72] Inventor: Robert W. McJones, 529 Via Del Monte,

Palos Verdes Estates, Calif. 90274 [22] Filed: Aug. 25, 1970 [21] Appl. No.: 66,817

[52] US. Cl ..73/359, 48/184, 73/420, 137/321 [51] Int. Cl. ..G0ll 19/00 [58] Field of Search ..73/420, 389; 137/321, 318; 48/184 [56] References Cited UNITED STATES PATENTS 1,524,042 1/1925 Lemdine "137/321 3,566,696 3/1971 Maddison et al. ..73/420 Primary Examiner-Donald O. Woodiel AttorneyChristie, Parker & l-lale [5 7] ABSTRACT An idle adjusting tool has a body adapted for mounting on a fuel-air mixer with a bore of the body opening into a fuel passage of the mixer. A spring biases a screwdriver blade, received in the bore, away from an idle adjusting screw of the mixer. Upon displacing the screwdriver blade against the force of the spring, it is possible to engage the idle adjusting screw. Gas pressure communication between the fuel passage and a pressure gauge connected to the tool exists through the bore.

9 Claims, 3 Drawing Figures IDLE ADJUSTING TOOL BACKGROUND OF THE INVENTION This invention relates to a tool for providing a pressure tap to measure gas pressure within a passage of a fuel-air mixer and for adjusting the position of a metering pin that controls idle gas flow through the mixer.

With the growing concern about air pollution caused by motor vehicles, several techniques have been devices to control air pollution from this source. One technique which has proven quite successful employs natural gas as a fuel for the engine of a vehicle. Gas is mixed with air in a fuel-air mixer before being burned in the engine. One fuel-air mixer which has been successfully implemented into natural gas fueled vehicles is basically described in US. Pat. No. 2,927,848 to Baverstock and is currently being manufactured by IMPCO Division of A. J. Industries, Cerritos, California, as Pacific Lighting Model 1.25 mixer. This mixer employs a diaphragm which is positionally responsive to engine air flow of a vehicle to supply the vehicle with fuel and air at a preset fuel-air ratio. Fuel enters the mixer through a passage and is admitted to a fuel chamber by a metering pin for mixing with air and aspiration into the engine. The position of the metering pin is adjustable for idle adjustment through an idle adjusting screw.

The idle adjusting screw in the fuel-air mixer just described is in a relatively inaccessible location and is not visible during adjustment. This occasions difficulties. Because the idle screw is carried by a flexible diaphragm, the downward force applied to the screwdriver by a mechanic often causes the diaphragm to be displaced during adjustment. With displacement of the diaphragm during adjustment, the idle fuel-air ratio cannot be adjusted correctly because upon the release of the displacement force, the metering pin changes position. In aggravated cases this can cause an engine to die and leave a mechanic with the difficult job of setting idle so that the engine will run again.

Accurate final fuel pressure regulator adjustments can be made by measuring the fuel pressure just upstream from the metering pin in order to avoid the effects of line loss. However, there has been no known method of doing this previously without relatively elaborate techniques.

SUMMARY OF THE INVENTION Briefly, this invention provides an idling adjusting tool for fuel-air mixers which produces a controlled idle adjustment and admits to metering fuel pressure at the metering pin of the mixer.

A specific form of the invention contemplates an idle adjusting tool having a body which, preferably, is adapted to be mounted, as by threads, on a fuel-air mixer axially of the mixer's idle adjusting screw. The body has an axial bore which opens at one end of the body for receiving wrenching means, typically a screwdriver blade. The wrenching means, in turn, has a shank which is provided with means such as longitudinal flutes for pressure communication between the bore and a fuel inlet passage of the fuel-air mixer. A pressure tap adapted for pressure communication with a pressure gauge and opening into the bore communicates with the inlet passage. Means are provided to bias the shank and its carried wrenching means into a withdrawn position in the bore. This means preferably includes a spring disposed concentrically about a stem attached to the shank and which extends outwardly of the body. The spring is in compressive engagement with a cap secured to the body and a knob secured to the stem.

A more detailed and preferred form of the present invention contemplates a pressure tap which includes a rotatable collar received by the body. The collar has means for pressure communication with a pressure gauge. These means may be a laterally extending tube adapted to receive a length of flexible tubing leading to the pressure gauge. An annular channel between the collar and the body and a port between the bore and the channel provides pressure communication to the channel. The rotatable feature of the collar avoids any problem with pressure gauge placement which might otherwise occur, for example, by a kink in the tubing. Preferably the cap is threaded onto an externally threaded portion of the body against a threaded locking collar to secure the cap firmly in place. An annular flange on the body is preferably provided for supporting the rotatable collar.

These and other features, aspects and advantages of the present invention will become apparent from the following description, appended claims and drawings.

BRIEF DESCRIPTION OF THE FIGURES FIG. 1 is an elevational view, partly in half section, of a preferred form of the idle adjusting tool of the present inventron;

FIG. 2 is a view of the idle adjusting tool of FIG. 1 with its blade extended; and

FIG. 3 is a view of the idle adjusting tool of the first two Figures in use.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIGS. 1 and 2, the preferred form of the idle adjusting tool of the present invention is indicated generally by reference numeral 10. The tool includes a body 12, a wrenching member 14, a pressure tap 16, a cap 18, a locking collar 20 and an actuating assembly 22.

A first end of the body has a threaded portion 24 adapted for temporarily securing the tool to a fuel-air mixer in position for the tool to engage the mixers idle adjusting screw. A frustoconical transition section 26 extends longitudinally of the threaded portion of the body to a right cylindrical section 28. The body necks in above the right cylindrical section to define an annular radial shoulder or flange 30 which supports and properly positions pressure tap 16. An annular channel 32 lies longitudinally above shoulder 30. This channel opens into an axial bore 34 of the body through one or more ports 36. Channel 32 is defined by an annular groove in the body and an axially extending annular inner surface of pressure tap 16.

An externally threaded portion 38 extends from the top of the body to a point adjacent pressure tap l6. Locking ring 20 and cap 18 are secured to the body by threaded engagement with the bodys threaded portion.

Wrenching member 14 includes a screwdriver blade 40 which is integral with shank 42. Shank 42 is essentially the same diameter as bore 34. As can best be seen in FIG. 2, the shank is so dimensioned longitudinally that in its extended position the top of the shank clears ports 36. One or more longitudinal flutes 44 extends the length of the shank for pressure communication between a fuel inlet passage of a fuel-air mixer and pressure tap 16. In the withdrawn position of the shank shown in FIG. 1, an annular external groove or channel 45 assures pressure communication to the pressure tap through ports 36. Pressure communication to a pressure gauge then is effected through pressure tap 16, ports 36, channel 45, flutes 44 and the fuel inlet passage of a fuel-air mixer.

Actuating assembly 22 includes an elongated stem 46 which extends longitudinally from its connection to shank 42 through a bore 48 of body 12 and a bore 50 in the top of cap 18. A knob 52 is secured to stem 46. A compression spring 54 acts between knob 52 and cap 18 to bias shank 42 and its screwdriver blade 40 into a retracted position within bore 34, as shown in FIG. 1. Knob 52 may be provided with knurled surface to facilitate gripping.

Pressure tap 16 includes an annular, rotatable collar 56 disposed radially of channel 32 and which rests on annular shoulder or flange 30. Collar 56 carries a tube 58 which has a bore 60 opening into channel 32.

Cap 18 has a knurled portion 62 for facilitating threading the cap onto and off of threaded body portion 38. The cap has a frustoconical transition section 64 between knurled portion 62 and a neck 66. If desired, means such as an O-ring can be disposed within bore 50 to provide a seal.

Locking ring 20, which may also be externally knurled as at 68, is threaded on threaded portion 38 between rotatable collar 56 and knurled portion 62 of cap 18. This locking ring or collar serves to secure cap 18 in place and provides a close tolerance for pressure tap 16 to avoid leaks into the pressure path between the tap and the fuel passage of a fuel-air mixer.

Before proceeding with the description of the operation of the idle adjusting tool of the present invention, the apparatus attendant with its operation will be briefly described with reference to FIG. 3. In this Figure reference numeral 70 represents a standard pressure gauge which is coupled through a length of flexible tubing 72 to pressure tap assembly 16 as by the tubings receipt on tube 58. Reference numeral 74 indicates a fuel-air mixer such as the type generally described in U.S. Pat. No. 2,927,848 to Baverstock. This type of fuel-air mixer employs a pressure sensitive diaphragm 76 secured in the body 78 of the mixer. A compression spring 80 between an interior surface of the body and a bridge 82 biases the diaphragm towards a closed position. Bridge 82 has a plurality of slots 84 for pressure communication between an upper chamber 86 and a passage 88, passage 88 leading to the carburetor inlet of an internal combustion engine. A valve member 90 is carried by diaphragm 76 for movement toward and away from a valve seat 92. The valve member has an axial passage 94 to communicate passage 88 with upper chamber 86 through slots 84. A lower chamber 96 is in pressure communication with atmosphere through slots 98. A fuel inlet passage 100 from a source of fuel, say, natural gaS, leads into upper chamber 86 through a passage 102. A metering pin 104 meters the amount of fuel passing between passage 100 and upper chamber 86. The metering pin has longitudinal slots 106 for the passage of fuel under low throttle conditions. The metering pin also has a washer 108 for providing a backing to a gasket 110 which can seat on a proximate surface of body 78. Metering pin 104 is carried by bridge 82 through idle adjustment screw 112. A spring 114 between bridge 82 and meterin g pin 104 provides a slight resistance to adjustment of the metering pin by the idle adjusting screw. The idle adjusting screw has a head with a slot 116 for engagement by blade 40. The position of metering pin 104 is determined by idle adjusting screw 112 and diaphragm 76. Engine air flow through the annular space between valve member 90 and valve seat 92 creates a pressure drop which is transmitted to chamber 86 through slots 84. The resulting pressure differential between chambers 96 and 86 acts upon diaphragm 76 and produce a force which is in equilibrium with the force due to spring 80. Thus, the position of bridge 82 is related to the engine air flow. Metering pin 104 moves with bridge 82 and allows a fuel flow which is in direct proportion to the air flow.

FIG. 3 illustrates the idle position of fuel-air mixer 74. In this position there is a slight clearance between gasket 110 and body 78 to admit to gas flow under the gasket through slots 106 into chamber 86. Fuel pressure as established by regulation is present in passage 100. A leak path for sensing this pressure is effected past the head of idle adjusting screw 112 at 118 into a secondary chamber 120.

The operation of idle adjustment tool will now be described. initially, the tool is threaded into threads 122 of mixer body 78 above idle adjusting screw 112. Pressure gauge 70 is connected to the tool by slipping tubing 72 over tube 58. The engine of the vehicle is started. The pressure within fuel inlet passage 100 is also present in secondary chamber 120 and is sensed by pressure gauge 70 by virtue of the pressure communication existing through flutes 44, channel 45, ports 36, channel 32 and bore 60 of tube 58. The upstream regulator is then adjusted as necessary to yield the specified pressure in passage 100. Next, knob 52 is depressed to engage screw 112 and the proper idle setting is established.

The idle adjusting tool of the present invention provides several advantages. Initially, it is capable of effecting idle adjustment of a fuel-air mixer even though the idle adjustment screw is in a blind location. Spring 54 provides positive pressure which tends to retract blade 40 and thereby prevent a false reading which would be occasioned by forcing gasket into a relatively closed position. In other words, spring 54 provides a means whereby the operator of the tool can sense engagement with the idle adjusting screw without applying a downward force to the screw which could give a faulty idle adjustment. Moreover, the idle adjusting tool of the present invention affords a means whereby the pressure in the fuel inlet of the fuel-air mixer is sensed where it is more important, that is, just upstream from the metering pin assembly. As a consequence, line losses will not affect the accuracy of the idle adjustment by producing a false reading by gauge 70. Moreover, the sensing of the pressure at the location afforded by the idle adjustment tool of the present invention is at a point where, if there is a malfunction of fuel delivery components upstream of the fuel-air mixer, that fact can readily be ascertained.

The present invention has been described with reference to a certain embodiment. The spirit and scope of the appended claims should not, however, necessarily be limited to the foregoing description.

What is claimed is:

1. An idle adjusting tool comprising:

a. a body having first and second longitudinally spaced apart ends, and a longitudinal bore opening at the first end;

b. a wrenching member disposed for longitudinal movement within the bore between a retracted position and an extended position spaced from the first end for engaging the idle adjustment screw of a fuel-air mixer;

0. means for biasing the wrenching member towards its retracted position;

(1. means for extending the wrenching member and for operating the wrenching member externally of the body;

e. a pressure tap adapted for pressure communication with a pressure gauge and opening into the bore at a point spaced from the first end; and

f. means for pressure communicating the open end of the bore with the pressure tap.

The idle adjusting tool claimed in claim 1 wherein:

a. the body has a first and a second section, the first section being proximate the first end and having a diameter larger than the second section, the second section extending longitudinally from the first section to the second end and meeting the first section at an annular radial flange; and

b. the pressure tap includes a rotatable collar rotationally received by the body on the flange, an annular channel defined by the rotatable collar and the body radially inward of the collar, and a port between the channel and the bore.

3. The idle adjusting tool claimed in claim 2 wherein:

a. the second section of the body is externally threaded; and

b. a cap is included which is in threaded engagement with the threads of the second section.

4. The idle adjusting tool claimed in claim 3 wherein:

a locking collar is included which is in threaded engagement with the threads of the second section between the rotatable collar and the cap for engagement with the cap to lock the latter in place.

5. The idle adjusting tool claimed in claim I wherein:

the wrenching member includes a shank of approximately the same diameter as the bore and disposed within the bore, the shank having at least one longitudinal external groove for pressure communicating the outside of the body with the pressure tap.

6. The idle adjustment tool claimed in claim 5 wherein:

a. the means for extending and operating the wrenching means includes a stem attached to the shank and extending longitudinally through the second end of the body, and a knob secured to the stem outside the body; and

b. the biasing means includes a compression spring disposed around the stem and acting between the body and the knob.

7. An idle adjusting tool comprising:

a. a body having a first and a second end, a fastening portion proximate the first end adapted to be removably secured to a fuel-air mixer in spaced relationship with an idle adjusting screw of the fuel-air mixer, and a bore extending longitudinally from the first end to a terminus within the body;

. a pressure tap assembly disposed longitudinally of the 5 a locking collar received by the body between the rotatable collar and the second end of the body;

. a cap received by the body over the second end thereof and adapted to be secured against rotation by engagement with the locking collar;

wrenching means for engaging the idle adjusting screw; a shank disposed for longitudinal movement in the bore between a retracted position and an extended position and having a first and a second end, the first end of the shank carrying the wrenching means, the shank in the extended position spacing the wrenching means from the first end of the body in position to engage the idle adjusting screw, the second end of the shank in the extended position being disposed in the bore, the shank having a diameter about the same as the diameter of the bore and at least one passage extending along a length of the shank for pressure communicating the pressure tap with the outside of the body;

g. a stem secured to the shank for movement therewith and extending longitudinally through the cap;

h. means on the stern for operating the wrenching means and extending the shank to its extended position; and

i. biasing means between the cap and the operating means for biasing the shank towards its retracted position.

8. The idle adjusting tool claimed in claim 7 wherein:

a. the body has an externally threaded portion extending from the second end thereof towards the first end to a terminus short of the rotatable collar; and

b. the locking collar and the cap are threadably received on the externally threaded portion of the body.

9. The idle adjusting tool claimed in claim 8 wherein:

the body has an external annular radial flange between the rotatable collar and the first end of the body, the rotatable collar being disposed on the flange. 

1. An idle adjusting tool comprising: a. a body having first and second longitudinally spaced apart ends, and a longitudinal bore opening at the first end; b. a wrenching member disposed for longitudinal movement within the bore between a retracted position and an extended position spaced from the first end for engaging the idle adjustment screw of a fuel-air mixer; c. means for biasing the wrenching member towards its retracted position; d. means for extending the wrenching member and for operating the wrenching member externally of the body; e. a pressure tap adapted for pressure communication with a pressure gauge and opening into the bore at a point spaced from the first end; and f. means for pressure communicating the open end of the bore with the pressure tap.
 2. The idle adjusting tool claimed in claim 1 wherein: a. the body has a first and a second section, the first section being proximate the first end and having a diameter larger than the second section, the second section extending longitudinally from the first section to the second end and meeting the first section at an annular radial flange; and b. the pressure tap includes a rotatable collar rotationally received by the body on the flange, an annular channel defined by the rotatable collar and the body radially inward of the collar, and a port between the channel and the bore.
 3. The idle adjusting tool claimed in claim 2 wherein: a. the second section of the body is externally threaded; And b. a cap is included which is in threaded engagement with the threads of the second section.
 4. The idle adjusting tool claimed in claim 3 wherein: a locking collar is included which is in threaded engagement with the threads of the second section between the rotatable collar and the cap for engagement with the cap to lock the latter in place.
 5. The idle adjusting tool claimed in claim 1 wherein: the wrenching member includes a shank of approximately the same diameter as the bore and disposed within the bore, the shank having at least one longitudinal external groove for pressure communicating the outside of the body with the pressure tap.
 6. The idle adjustment tool claimed in claim 5 wherein: a. the means for extending and operating the wrenching means includes a stem attached to the shank and extending longitudinally through the second end of the body, and a knob secured to the stem outside the body; and b. the biasing means includes a compression spring disposed around the stem and acting between the body and the knob.
 7. An idle adjusting tool comprising: a. a body having a first and a second end, a fastening portion proximate the first end adapted to be removably secured to a fuel-air mixer in spaced relationship with an idle adjusting screw of the fuel-air mixer, and a bore extending longitudinally from the first end to a terminus within the body; b. a pressure tap assembly disposed longitudinally of the fastening portion on the body including a rotatable collar rotationally received by the body, means carried by the collar for pressure communication with a pressure gauge, an annular channel defined by the rotatable collar and the body in pressure communication with the pressure gauge communication means, and a port between the channel and the bore; c. a locking collar received by the body between the rotatable collar and the second end of the body; d. a cap received by the body over the second end thereof and adapted to be secured against rotation by engagement with the locking collar; e. wrenching means for engaging the idle adjusting screw; f. a shank disposed for longitudinal movement in the bore between a retracted position and an extended position and having a first and a second end, the first end of the shank carrying the wrenching means, the shank in the extended position spacing the wrenching means from the first end of the body in position to engage the idle adjusting screw, the second end of the shank in the extended position being disposed in the bore, the shank having a diameter about the same as the diameter of the bore and at least one passage extending along a length of the shank for pressure communicating the pressure tap with the outside of the body; g. a stem secured to the shank for movement therewith and extending longitudinally through the cap; h. means on the stem for operating the wrenching means and extending the shank to its extended position; and i. biasing means between the cap and the operating means for biasing the shank towards its retracted position.
 8. The idle adjusting tool claimed in claim 7 wherein: a. the body has an externally threaded portion extending from the second end thereof towards the first end to a terminus short of the rotatable collar; and b. the locking collar and the cap are threadably received on the externally threaded portion of the body.
 9. The idle adjusting tool claimed in claim 8 wherein: the body has an external annular radial flange between the rotatable collar and the first end of the body, the rotatable collar being disposed on the flange. 